Technology Review - 11 Jun 09

Waterproof power: This protective casing envelops a
functioning lithium-metal battery electrode, excluding water
but letting oxygen pass. It's part of a prototype battery
made by PolyPlus Battery of Berkeley, CA. Credit:
PolyPlus

IBM Invests in Battery Research

By Katherine Bourzac
Thursday, June 11, 2009

IBM Research is beginning an ambitious project that
it hopes will lead to the commercialization of batteries that store 10
times as much energy as today's within the next five years. The company
will partner with U.S. national labs to develop a promising but
controversial technology that uses energy-dense but highly flammable
lithium metal to react with oxygen in the air. The payoff, says the
company, will be a lightweight, powerful, and rechargeable battery for
the electrical grid and the electrification of transportation.

Lithium metal-air batteries can store a tremendous
amount of energy--in theory, more than 5,000 watt-hours per kilogram.
That's more than ten-times as much as today's high-performance
lithium-ion batteries, and more than another class of energy-storage
devices: fuel cells. Instead of containing a second reactant inside the
cell, these batteries react with oxygen in the air that's pulled in as
needed, making them lightweight and compact.

IBM is pursuing the risky technology instead of
lithium-ion batteries because it has the potential to reach high enough
energy densities to change the transportation system, says Chandrasekhar
Narayan, manager of science and technology at IBM's Almaden Research
Center, in San Jose, CA. "With all foreseeable developments, lithium-ion
batteries are only going to get about two times better than they are
today," he says. "To really make an impact on transportation and on the
grid, you need higher energy density than that." One of the project's
goals, says Narayan, is a lightweight 500-mile battery for a family car.
The Chevy Volt can go 40 miles before using the gas tank, and Tesla
Motors' Model S line can travel up to 300 miles without a recharge.

One of the main challenges in making lithium
metal-air batteries is that "air isn't just oxygen," says Jeff Dahn, a
professor of materials science at Dalhousie University, in Nova Scotia.
Where there's air there's moisture, and "humidity is the death of
lithium," says Dahn. When lithium metal meets water, an explosive
reaction ensues. These batteries will require protective membranes that
exclude water but let in oxygen, and are stable over time.

IBM does not currently have battery research programs
in place. However, Narayan says that IBM has the expertise needed to
tackle the science problems. In addition to Oak Ridge, IBM will partner
with Lawrence Berkeley, Lawrence Livermore, Argonne, and Pacific
Northwest national labs. The company and its collaborators are currently
working on a proposal for funding from the U.S. Department of Energy
under the Advanced Research Projects Agency-Energy.

Research on lithium-metal batteries stalled about 20
years ago. In 1989, Canadian company Moli Energy recalled its
rechargeable lithium-metal batteries, which used not air but a more
traditional cathode, after one caught fire; the incident led to legal
action, and the company declared bankruptcy. Soon after, Sony brought to
market the first rechargeable lithium-ion batteries, which were safer,
and research on lithium-metal electrodes slowed nearly to a halt. (After
restructuring, Moli Energy refocused its research efforts and is now
selling lithium-ion batteries under the name Molicel.) Only a handful of
labs around the world, including those at PolyPlus Battery, in Berkeley,
CA, Japan's AIST, and St. Andrews University, in Scotland, are currently
working on lithium-air batteries.